1. Field Of The Invention
The present invention relates to a detecting device for expanding an air bag upon collision of a vehicle so as to protect a driver safely before crash.
2. Description Of The Prior Art
As well known recently, apparatus have been developed that expand an air bag upon collision of a vehicle to prevent a driver from crashing on to a steering wheel, a front window, an instrument panel etc., thereby accidents resulting in loss of human life can be eliminated effectively.
In this case, a detecting time for expansion of an air bag is an important problem and influences and affects filling of an air bag, therefore slow action frequently cannot protect a driver safely.
Performance of a sensor of this sort in the prior art is that of a movable member transferred by deceleration produced at collision in no-brake condition or sudden brake action just before an obstacle is struck and the movable member contacts with an opposite contact member, thereby an electric circuit for acting an the air bag is closed to open a gas valve so that expanded gas is introduced into the air bag.
The above performance corresponds to an integral of a second order with respect to "deceleration" converted into "displacement."